Hey everyone. This totally confuses me in several ways, so here it goes. It was around 10F here in upstate NY. When I put my car into reverse after moving forward and sometimes into drive after moving backwards, I hear a pop or soft bang coming from under the car. I can especially hear it if the window is open and yes, I do feel it going into gear. The car seems to be driving normally with no other sounds. This has been happening over the past week, especially when it is cold. I just had the transmission fluid changed with a deep pan installed plus a 1/2 qt of Lucas put in (full quart was used last fluid flush). I also had a B&M transmission cooler installed last year. Just recently, I also had to have the rear diff pinion seal replaced and I just changed the fluids in both diffs and the transfer case (and there are no leaks). A few months ago I changed the throttle position sensor and it improved shifts a bit.

It is only doing it after the car has been sitting for a couple hours. The first few shifts into reverse or sometimes drive if I was moving in reverse are hard and louder than usual. After driving a few miles or 10-15 minutes, it doesn't do it nearly as loud or even at all. The jolt can be about the same, but no bang.

Also, I did notice that the noise is worse when the truck is in 4LO and the jolt that the car makes when it goes into gear is more intense.

No leaks and there is Lucas 80W-90 in both diffs and MAXLIFE ATF in the transfer case and transmission (all new fluids).